Geographical Centrality as an Explanation for Regional Differences in Intelligence

Edward Miller

Abstract

The theory proposed in this paper explains the spread of recently originated alleles (genetic variants) favorable to higher cognitive ability and similar traits. It applies to alleles that arose as new mutations during or after the modern human exodus from Africa. The theory proposes that such mutations (1) occurred in proportion to the size of the population, thus increasing genetic variance for cognitive traits in large relative to small populations; (2) were under positive selection, although the strength of selection was variable in different ecosystems; (3) spread slowly in stationary populations depending on the number of tribal boundaries that needed to be crossed; (4) could spread faster in sparsely populated areas in which the mobility of the population was higher. New reasons for stronger selection for intelligence in cold climates include less selection for disease resistance and the intellectual demands of mate selection. The theory explains the earlier evolution of civilizations on the Eurasian landmass than elsewhere, attributed to the genetic interchanges on the “genetic freeway” of the Eurasian steppe, and the relative backwardness of historically smaller and more isolated populations such as Australian Aborigines and Native Americans.